Magnetic storage media is used in a variety of technologies for providing storage of data, processing, and other functionality to electronic and magnetic devices. Patterning and non-patterning techniques are employed to spatially define features having different electrical or magnetic properties. Moreover, various patterning and non-patterning techniques are used as part of the fabrication process for building a wide variety of semiconductor and magnetic patterned media.
Patterned or spatially defined features in magnetic data storage media are used for storing digital data that can be erased and rewritten. Magnetic data storage media can be used in memory devices, such as MRAM and magnetic logic, and is being developed for use in storage devices, such as disk or tape drives. Generally, magnetic media on a disk or tape substrate can be referred to as either bit-patterned or non-patterned magnetic media. In bit-patterned magnetic media for storage devices, some of the patterned features are designed as storage elements of digital bits of data and other patterned features are designed for functions, such as providing servo information to position a read/write head.
Several techniques are known for patterning bit-patterned magnetic media. Prior techniques relied on an etching process for forming the patterns of storage elements in data storage media. However, such techniques required the planarization of the etched disk, which can result in increased cost and labor, as well as a reduction in yield. Accordingly, recently there has been a desire to develop certain techniques to mitigate the shortcomings of etching-based processes. For example, masked ion-beam and masked plasma immersion ion implantation lithography has proven to be an efficient alternative for producing patterned media.
Similar to patterned magnetic media, electronic devices, such as semiconductor data storage devices, utilize etching and ion implantation techniques for forming a pattern of doped regions in a medium. In the case of implanted ions, the energized ions cause the electrical properties of the doped regions in the medium to change from an initial value of the medium (e.g., semiconductor medium), thereby leaving un-doped regions covered by the hard mask between the doped regions.
Although known techniques for forming data storage media provide some advantages, such techniques also introduce certain disadvantages. For example, current techniques for forming patterned media, such as perpendicular magnetic recording media or thermal assisted recording media, results in a relatively high surface roughness of the media compared to past techniques, such as those associated with longitudinal magnetic recording media. Increased surface roughness may lead to non-uniform overcoat or top layer coverage, increased magnetic spacing in the case of magnetic media, and various flyability issues associated with data storage devices. To reduce surface roughness of finished data storage media (e.g., disk), conventional techniques employ a burnishing process to smooth the surface of the media. However, burnishing may introduce scratches and increase the risk of humidity-induced corrosion on the surfaces of the media, particularly with perpendicular recording media or thermal assisted recording media, which are known to have a significantly high final surface roughness. Other approaches for reducing surface roughness of data storage media include etching non-magnetic filler layers within the media, etching a substrate of the media prior to deposition of a magnetic layer and overcoat layer, and etching a surface of the data storage media at a normal angle relative to the surface of the media.